Playing an exceptional role in plant and animal biodiversity, the hedgerow, which fell into disuse at the end of the last century, is making a strong comeback in farming practices. A complex ecosystem, it plays a protective role for the soil, crops and livestock but also has an ornamental function.
What is a hedgerow?
A hedge is a hedge composed of several species of trees and shrubs arranged in differentiated layers. Generally, it is made up of local, indigenous plants, which grow without worry and are adapted to both the climate and the soil of the region. In the past, this hedge served as a property boundary between cultivated plots and as a natural fence for livestock. This type of hedge was the basis of the famous bocages that shaped the landscape in many regions, providing firewood and delimiting plots so beautifully.
The great economic projects of intensive reparcelling between 1960 and 1980 were the reason of this so particular landscape, leaving place to the green deserts of the intensive agriculture and all the problems which are linked to them.
Composition of a hedgerow
This very diversified hedge includes a tree part with high trees (ash, beech, rowan, oak...), a shrub zone composed of bushes and shrubs such as hawthorn, viburnum, broom, holly, fusain, blackthorn or bramble, and a herbaceous zone at its foot with local plants growing spontaneously such as mallow, poppy, vulpine or clover. This plant diversity offers numerous shelters to a very varied and useful fauna. In the tree layer, birds (including birds of prey) watch over the crops, capturing parasitic insects, but also rodents and other small mammals. The tall trees are sometimes replaced or associated with trees in the form of a hedge such as hornbeam, alder, white willow or wild apple.
The shrub layer shelters a very varied fauna, birds but also insects and mammals; it often serves as a nesting area. Flowering over a long period of time and providing a variety of berries for many months, it is a choice larder for wildlife that is attracted en masse.
The herbaceous zone attracts pollinating insects, but also serves as a breeding area and biological corridor for animal movement, especially in agricultural areas. The wider the strip, the more beneficial animals will be present.
Often the herbaceous zone is located at the foot of a slope, a very common feature in bocages. The embankment compensates for certain effects of the wind and modulates them. It also has the function of slowing down the flow of rainwater and limiting the erosion of the land.
Further down, at the base of the slope, a ditch is often built to stop the progression of tree roots on the surface (which would compete with the crops) and encourage their vertical rooting. It serves as a drainage and storage area for rainwater and is often home to a wide variety of batrachians, insects and reptiles.
Interests of the plantation of a hedge bocagère
This type of very diversified hedge has many advantages on a technical, economic and environmental level.
Technical and economic advantages
- The hedge serves as a natural fence and requires little maintenance;
- It can be a source of firewood and work to be done on site (stakes, tool shed, gate ...);
- It provides a harvest of fruits and berries depending on the species planted;
- It protects from the wind;
- It has an undeniable aesthetic aspect in the landscape and constitutes an element of identity in certain regions.
- Leisure and educational activities are organized by tourism actors around the concept of the discovery of this form of development that are the hedgerows and the hedges that constitute them. Creation of hiking trails, mountain bike trails, horseback riding, bird and wildlife observation tours, but also discovery trails on the various typical pruning techniques (pollards, hornbeams, plessage...) attract many tourists in these rural areas.
Environmental benefits
- The hedgerow is a reservoir for both animal and plant biodiversity, it allows to recreate a balance between prey and predators. The crops protected by the auxiliaries are less subject to treatment products.
- It is a source of humus.
- This type of landscaping helps to fight effectively against soil erosion and nutrient leakage.
- Planted perpendicular to the slope, it favors water penetration in the soil.
- The slope plays an important role in draining and filtering water if it is overloaded with inputs. Pollutants such as phosphates and nitrates are thus fixed and transformed before they enter the water table.
